program define nlNLStest
	if "`1'" == "?" { /* if query call ... */
			global S_1 "B0 B1" /* declare parameters */ 
			global B0=1 /* and initialize them */ 
			global B1=.1
			exit
	}
	replace `1'=$B0*(1-exp(-$B1*`2'))	 /* otherwise, calculate function */
end 
